The present invention relates to loop circuits in a switchboard connected to an exchange and, more particularly, to a switchboard terminal apparatus in which a switchboard operator operates four to six or more loops.
In a conventional switchboard loop circuit system, a switchboard terminal, e.g., an attendant console in a small-scale system has displays and keys/lamps controllers respectively corresponding to loops arranged in the switchboard terminal. A switchboard operator performs multiloop operations by the number of loop circuits arranged in the switchboard. For example, if the switchboard terminal has six loop circuits, the switchboard operator can simultaneously handle a maximum of six calls, and the seventh or subsequent incoming calls to the switchboard are set in a queue to wait for idle loop circuits.
When the switchboard operator has finished an operation for a given call and performs its release operation, and if the given call is put in a calling state for the extension subscriber and no answer is made within a predetermined period of time, a reentering request of the switchboard operator is made. In this case, the given call is kept held while being kept connected to a loop circuit. However, when the given call does not request for a reentering of the switchboard operator, the given call is released from the loop circuit, and this loop circuit becomes idle. This circuit is then used for the next incoming call or an outgoing call from the switchboard operator.
In the above conventional switchboard loop circuit system, in order to increase the number of calls simultaneously handled by the switchboard operator, the number of loop circuits included in the switchboard terminal must be increased, and at the same time the capacities of terminal screen displays and keys/lamps must also be increased accordingly. It is difficult to arrange seven or more loop circuits in the conventional switchboard loop circuit system in practice.
In a call release request operation by the switchboard operator, when a reentering request of the switchboard operator is predicted, a call is kept held while being kept connected to a loop circuit regardless of actual generation/non-generation of a reentering request. As a result, the loop circuit is invalidly kept held.